They've been overpaid, underpaid and not paid at all - now one teacher has been paid for being in two places at one time.

In the latest round of Novopay botches, the relief teacher was paid for working at schools in Upper Hutt and Auckland on the same day.

The Upper Hutt school, which did not want to be named, joked that a classroom of children must have been left reading silently, while their teacher caught a plane to Auckland.

This week's pay cycle gave one teacher thousands of dollars more than they were owed, when they were paid for 39 days, instead of 39 hours.

And Fergusson Intermediate School deputy principal Shirley Porteous, of Upper Hutt, was randomly demoted by the new payroll system, so she supposedly now owes Novopay $1500.

Teacher unions and Labour education spokeswoman Nanaia Mahuta are demanding a parliamentary inquiry into the Education Ministry's system, which was introduced nearly three months ago.

Wellington Wairarapa School Trustees Association management committee member Wendy Eyles said she was astounded by the "bizarre" errors.

School staff were spending about two days a week purely on chasing up Novopay problems. "The buck has to stop somewhere. We get money to deliver education, not to deliver administration of payroll," Mrs Eyles said. "That cost has just been shifted on to schools, which means less money spent on education."

Mrs Porteous's pay problems started this week, when her management units and allowances were suddenly stripped from her pay package. And because it was done in arrears, she is, in effect, working this week for free.

With her mortgage and credit card payments due, she has had to be funded by the school until the fault is fixed.

"I am absolutely gutted," she said. "It's incredibly frustrating and also very hard for your family to say: ‘Well, I have no pay this week.'

"Luckily I have a very understanding husband and a school that will help me out."

Ms Mahuta called yesterday for Parliament's education and science select committee to hold an inquiry into the "stuff-ups".

NZEI also demanded this week a full public inquiry.

Education Ministry group manager Rebecca Elvy said Australian contractor Talent2 would be financially penalised for failure to meet required service levels, but she would not say how much.

The ministry, which does not use Novopay to pay its own staff, would not directly compensate staff for time spent on Novopay issues, she said. But it would reimburse travel and attendance costs for attending training roadshows.

There were 92,465 school staff successfully paid this cycle, with 15 non-payments identified by yesterday afternoon.

The backlog of priority problems had decreased from 8000 a month ago, to about 460.

Associate Education Minister Craig Foss said yesterday: "The backlog is down to just under 500, so good progress has been made, but still not enough.

"How has this happened? Total underestimation of the need for the call centre to be responsive in a timely manner, particularly from the first two pay periods, and that's compounded itself over recent weeks.

"It's totally unsatisfactory what's happened. I took on board the recommendation from the Novopay board for it to be implemented as is, [and was] given assurances about the functionality of it . . . but what has really let me down, and made me pretty angry, is the lack of delivery on commitments and assurances that I've been given over recent weeks."

$100.5M BOUGHT PROBLEMS

The Education Ministry agreed to pay Australian company Talent2 $100.5 million to build and run its Novopay payroll system for eight years, a ministry spokesman says.

The figure is far larger than the $29.4m capital cost of the system or the figure of $62.4m originally attributed to the contract in 2007, which included seven years' running costs.

Talent2 agreed to meet certain confidential performance targets as part of the contract and it could face undisclosed penalties if it misses them. The ministry has so far been unable to clarify when Talent2's performance against the contract will first be measured.

Noel Reid, chief executive of Auckland payroll company AMS, which registered interest in supplying the new payroll system but failed to make the ministry's shortlist, said he hoped problems with the system would encourage the Government to buy locally in future.

Candace Kinser, chief executive of information technology industry body NZICT, said she was concerned the Novopay debacle would reflect badly on the IT industry as a whole.

Talent2 delisted from the Australian stock exchange in August and is privately owned.